                                                                    (normalize-token unit))})))
 
 (s/defn ^:ql ^:always-validate expression :- ExpressionRef
+  {:added "0.17.0"}
   [expression-name :- (s/cond-pre s/Str s/Keyword)]
   (i/strict-map->ExpressionRef {:expression-name (name expression-name)}))
 


(s/defn ^:ql ^:always-validate expressions
  "Top-level clause. Add additional calculated fields to a query."
  [query, m :- {s/Keyword Expression}]
  (assoc query :expressions m))


;;; ## filter

(s/defn ^:private ^:always-validate compound-filter :- i/Filter
  ([compound-type, subclause :- i/Filter]
   (log/warn (u/format-color 'yellow "You shouldn't specify an %s filter with only one subclause." compound-type))
   subclause)

